Interpretive Summary: Anthracnose is a disease of sorghum that can severely reduce grain production and quality. Resistance is the best method of controlling the disease. To identy new sources of resistance, 300 accessions from the Sudanese sorghum germplasm collection were evaluated in Texas and Puerto Rico. Nearly half of the accessions conditioned a resistant response at both locations suggesting that the Sudanese germplasm collection is a potential source of diversity for anthracnose resistance. Variation in disease response for individual accessions was observed between locations, which would indicate that variation is also present in the pathogen. Breeders and researchers working on sorghum improvement will greatly benefit from the anthracnose resistant germplasm identified in this study. Determining the genetic mechanisms of resistance and variation within the pathogen will also aid in the development and deployment of resistant hybrids to reduce losses from the disease.

Technical Abstract:
The response to sorghum anthracnose (Colletotrichum sublineolum) was evaluated for 300 sorghum accessions from the Sudanese germplasm collection. The evaluation was conducted during the 2002 growing season in Texas and Puerto Rico using artificial inoculation methods. Nearly half of the accessions conditioned a highly resistant or resistant response at both locations, which corresponded to 137 accessions. Ten accessions conditioned a moderately susceptible response and 13 were susceptible or highly susceptible to the disease. Variation in the disease response between locations was observed for 142 accessions. Twenty accessions that showed resistant reactions in Puerto Rico exhibited susceptible reactions in Texas while seven accessions that were resistant in Texas exhibited susceptible reactions in Puerto Rico. These results indicate possible differences in the racial profile of the pathogen at the two locations. Genetic variation for anthracnose resistance or different mechanisms of resistance in the host may also be present; thus, these factors controlling resistance need to be elucidated to efficiently utilize the germplasm. Since a large number of the resistant accessions were observed for the Sudanese collection, this germplasm would be a valuable source for the identification of additional genes for anthracnose resistance.